EP1421630B1 - Method of depositing an oxide layer on a substrate and a photovoltaic cell using said substrate - Google Patents

Method of depositing an oxide layer on a substrate and a photovoltaic cell using said substrate Download PDF

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EP1421630B1
EP1421630B1 EP02754092A EP02754092A EP1421630B1 EP 1421630 B1 EP1421630 B1 EP 1421630B1 EP 02754092 A EP02754092 A EP 02754092A EP 02754092 A EP02754092 A EP 02754092A EP 1421630 B1 EP1421630 B1 EP 1421630B1
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Prior art keywords
substrate
chamber
depositing
oxide layer
sources
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French (fr)
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EP1421630A2 (en
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Ulrich Kroll
Johannes Meier
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Universite de Neuchatel
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Universite de Neuchatel
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1884—Manufacture of transparent electrodes, e.g. TCO, ITO
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/075—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PIN type, e.g. amorphous silicon PIN solar cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/548—Amorphous silicon PV cells

Definitions

  • the present invention relates to a method of depositing a transparent oxide layer on a substrate, which is particularly applicable to the manufacture of a photovoltaic cell, also called solar cell.
  • the invention also relates to such a cell whose transparent oxide layer is deposited according to this method.
  • the most technologically advanced solar cells comprise a substrate, a transparent conductive oxide (TCO) conductive oxide layer deposited on the substrate and a photovoltaically active layer deposited on the oxide layer.
  • This photosensitive layer is advantageously composed of three sub-layers of amorphous hydrogenated silicon, microcrystalline or nanocrystalline forming a p-i-n junction. More precisely, the two external sublayers are respectively positively and negatively doped, while the intermediate sublayer is intrinsic.
  • a cell of this type is described in detail, for example, according to several embodiments, in WO 97/24769.
  • US-A-5,002,796 discloses a method for depositing a transparent conductive oxide layer which consists in providing sources containing an oxygen-based liquid compound.
  • photovoltaic cells generally use a transparent conductive oxide layer made of tin dioxide (SnO 2 ) or zinc oxide (ZnO) deposited on a glass substrate by the chemical vaporization process. known under the abbreviation CVD (Chemical Vapor Deposition), which is carried out at a temperature generally between 400 and 550 ° C.
  • CVD Chemical Vapor Deposition
  • U.S. Patent No. 5,252,140 discloses a solar cell on tempered glass in which the soaking is performed after formation of the oxide layer. To avoid degradation thereof, heating is carried out at 650 ° C maximum for less than 2 minutes, before being rapidly cooled by air. These precautions, however, increase the process and do not guarantee the quality of the soaking.
  • US Pat. Nos. 4,751,149 and 5,002,796 disclose methods of depositing the vapor phase oxide layer in which the chemical compounds participating in the reaction are brought to the chamber by a carrier gas saturated with these compounds by bubbling.
  • Such a method makes it possible, of course, to have softer reaction conditions, which do not alter the properties of the substrate, and therefore to be used, in particular, for the production of solar cells on tempered glass.
  • the method does not allow good control of the amount of reagents involved, because the thermodynamic equilibrium that governs the saturation threshold of the carrier gas strongly depends on the temperature and the flow of this gas. Since it is problematic to precisely set the temperature in the entire circuit, there is a risk of uncontrolled recondensation of reagents in a colder place of the installation. The regularity and reproducibility of the layer are, therefore, quite difficult to ensure.
  • the chemical vaporization is carried out in a plasma of the deposition gases, formed inside the pregnant, preferably using the technique of PECVD (Plasma Enhanced Chemical Vapor Deposition), well known to those skilled in the art.
  • PECVD Pulsma Enhanced Chemical Vapor Deposition
  • the active layer of the cell comprises three sub-layers of amorphous, microcrystalline or nanocrystalline hydrogenated silicon forming a p-i-n junction, the two external sublayers being respectively positively and negatively doped.
  • the substrate is made of glass, preferably tempered glass, but it can also be made of stainless steel, aluminum or a polymer.
  • the cell shown in FIG. 1 uses as substrate a thin tempered glass plate, having a thickness of the order of 1 to 8 mm, on which is deposited a transparent conductive oxide (TCO) layer 12 having, typically, a thickness of 0.2 to 4 ⁇ m.
  • TCO transparent conductive oxide
  • the layer 12 advantageously consisting of tin dioxide (SnO 2 ), zinc oxide (ZnO) or an oxide of tin and zinc, is deposited by chemical vaporization (CVD) according to a process which will be described further.
  • a photovoltaic active layer 14 having a thickness of about 0.2 to 10 ⁇ m, is deposited on the oxide layer 12. It is composed of three sublayers of amorphous hydrogenated silicon, microcrystalline or nanocrystalline 16, 18 and 20, forming a pine junction. The two outer sublayers 16 and 20 are respectively positively and negatively doped.
  • the cell further comprises a rear contact layer 22, for example zinc oxide, deposited on the active layer 14 and a reflective layer 24, for example silver or aluminum, deposited on the layer 22.
  • a rear contact layer 22 for example zinc oxide
  • a reflective layer 24 for example silver or aluminum
  • FIG. 2 shows the equipment for the CVD deposition of a layer of zinc oxide 12 on the tempered glass plate 10.
  • a sealed chamber with a heating support 28 on which is deposited the tempered glass plate.
  • the chamber 26 is connected to a vacuum pump 30 and three reservoirs 32, 34 and 36 containing, first, water, the second, diethyl (C 2 H 5 ) 2 Zn and the third, a dopant, advantageously in the form of diborane (B 2 H 6 ).
  • B 2 H 6 diborane
  • the contents of the two tanks 32 and 34 are liquid, while that of the tank 36 is a gaseous mixture of 0.5 to 2% of diborane diluted in a gas such as nitrogen, argon or hydrogen. It will be noted that the tanks 32 and 34 are connected directly to the enclosure.
  • the reservoir 36 is pre-connected to the supply conduit of the reservoir 34, but it can also be connected directly to the enclosure.
  • the enclosure 26 is carried, using the heating support 28, at a temperature of about 180 ° C, but may be between 130 and 300 ° C, while the pump 30 lowers the pressure at a value of 0.3 to 0.5 mbar, but which can be between 0.01 and 20 mbar.
  • the adjustable valves (not shown) connecting the reservoirs 32, 34 and 36 to the enclosure 26 are then open.
  • the diethylzinc and the water contained therein in the liquid state evaporate on their surface and the resulting gases sucked into the chamber, react with each other and with the doping gas (B 2 H 6 ) to cause, at the temperature of the substrate, according to a known reaction, the deposition of the desired zinc oxide layer 12 on the tempered glass plate 10.
  • the tempered glass Since the operation takes place at a relatively low temperature, the tempered glass undergoes no deterioration of its properties. Moreover, given the homogeneous and low pressure prevailing in the installation, the gases sprays are not likely to recondense before admission to the enclosure.
  • the above method is ideal for depositing zinc oxide doped with diborane because the chemical reactions involved are without problems at the temperatures mentioned.
  • a CVD deposition of tin dioxide or a deposit of zinc oxide with a more stable dopant such as methyl tetrafluoride (CF 4 ) these temperatures are too low for that the reactions take place normally.
  • the deposition of the oxide layer is then carried out by the PECVD plasma chemical vaporization method.
  • the enclosure 26 is equipped with an electrode, for example in the form of a grid 38, disposed above the heating support 28 and an electric generator 40 is connected between this electrode and the support.
  • the gases introduced into the chamber 26 give rise to the formation of a plasma between the electrode 38 and the support 28. Active radicals are thus generated by the plasma and allow the chemical reactions giving rise to the deposition of the oxide layer to be at a temperature substantially lower than that normally required, thus preserving the properties of the substrate.
  • the tanks 34 and 36 respectively contain, for example, tetramethyltin (CH 3 ) 4 Sn and, as a dopant, methyl tetrafluoride (CF 4 ). It goes without saying that other compounds, well known in the art, can be used.
  • the water in the reservoir 32 may be replaced by any oxygen-containing compound (N 2 O, CH 3 OH, C 2 H 5 OH, ...) and that the dopant contained in the reservoir 36 may also be be in liquid form.

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  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Microelectronics & Electronic Packaging (AREA)
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  • Hybrid Cells (AREA)

Abstract

The invention relates to a method of depositing a transparent conductive oxide layer (12) on a tempered glass substrate (10) which is disposed inside a chamber (26). The inventive method consists in: providing sources (32, 34, 36) which contain an oxygen-based liquid compound, a liquid compound of the metal that is intended to form the oxide and a gas or liquid dopant respectively; establishing a temperature of between 130 and 300 °C and pressure of between 0.01 and 2 mbar in the chamber; and putting the sources in communication with said chamber. In this way, the liquids are vaporised at the surface thereof, sucked into the chamber without any need for a carrier gas and made to react with the dopant such that the oxide layer forms on the substrate.

Description

La présente invention concerne un procédé de dépôt d'une couche d'oxyde transparent sur un substrat, qui s'applique particulièrement bien à la fabrication d'une cellule photovoltaïque, également désignée cellule solaire. L'invention concerne aussi une telle cellule dont la couche d'oxyde transparent est déposée selon ce procédé.The present invention relates to a method of depositing a transparent oxide layer on a substrate, which is particularly applicable to the manufacture of a photovoltaic cell, also called solar cell. The invention also relates to such a cell whose transparent oxide layer is deposited according to this method.

Les cellules solaires les plus avancées technologiquement, à ce jour, comportent un substrat, une couche d'oxyde conducteur transparent TCO (Transparent Conductive Oxide) déposée sur le substrat et une couche photovoltaïquement active déposée sur la couche d'oxyde. Cette couche photosensible est avantageusement composée de trois sous-couches de silicium hydrogéné amorphe, microcristallin ou nanocristallin formant une jonction p-i-n. Plus précisément, les deux sous-couches externes sont respectivement dopées positivement et négativement, tandis que la sous-couche intermédiaire est intrinsèque.The most technologically advanced solar cells, to date, comprise a substrate, a transparent conductive oxide (TCO) conductive oxide layer deposited on the substrate and a photovoltaically active layer deposited on the oxide layer. This photosensitive layer is advantageously composed of three sub-layers of amorphous hydrogenated silicon, microcrystalline or nanocrystalline forming a p-i-n junction. More precisely, the two external sublayers are respectively positively and negatively doped, while the intermediate sublayer is intrinsic.

Une cellule de ce type est décrite en détail, par exemple, selon plusieurs formes de réalisation, dans la demande WO 97/24769.A cell of this type is described in detail, for example, according to several embodiments, in WO 97/24769.

Le document US-A-5 002 796 décrit un procédé de dépôt d'une couche d'oxyde conducteur transparent qui consiste à se doter de sources contenant un composé liquide à base d'oxygène.US-A-5,002,796 discloses a method for depositing a transparent conductive oxide layer which consists in providing sources containing an oxygen-based liquid compound.

Dans l'état actuel de la technique, les cellules photovoltaïques utilisent généralement une couche d'oxyde conducteur transparent réalisée en dioxyde d'étain (SnO2) ou oxyde de zinc (ZnO) déposée sur un substrat en verre par le procédé de vaporisation chimique connu sous l'abréviation CVD (Chemical Vapor Deposition), qui s'effectue à une température généralement comprise entre 400 et 550 °C.In the current state of the art, photovoltaic cells generally use a transparent conductive oxide layer made of tin dioxide (SnO 2 ) or zinc oxide (ZnO) deposited on a glass substrate by the chemical vaporization process. known under the abbreviation CVD (Chemical Vapor Deposition), which is carried out at a temperature generally between 400 and 550 ° C.

Or, il est particulièrement intéressant de pouvoir déposer la couche d'oxyde à une température inférieure car cela permettrait d'utiliser un substrat, tel que le verre trempé, qui répond aux normes de sécurité exigées pour une application à l'extérieur.However, it is particularly interesting to be able to deposit the oxide layer at a lower temperature as this would make it possible to use a substrate, such as toughened glass, which meets the safety standards required for an outside application.

Malheureusement, les températures mentionnées ci-dessus ont pour effet d'altérer les propriétés du substrat qui lui ont été conférées par le trempage.Unfortunately, the temperatures mentioned above have the effect of altering the properties of the substrate that have been imparted to it by soaking.

Le brevet US 5 252 140 décrit une cellule solaire sur verre trempé dans laquelle le trempage est effectué après le formation de la couche d'oxyde. Afin d'éviter la dégradation de celle-ci, le chauffage est effectué à 650 °C maximum pendant moins de 2 minutes, avant d'être rapidement refroidie par de l'air. Ces précautions renchérissent toutefois le procédé et ne garantissent pas la qualité du trempage.U.S. Patent No. 5,252,140 discloses a solar cell on tempered glass in which the soaking is performed after formation of the oxide layer. To avoid degradation thereof, heating is carried out at 650 ° C maximum for less than 2 minutes, before being rapidly cooled by air. These precautions, however, increase the process and do not guarantee the quality of the soaking.

A ce jour, on doit donc se contenter généralement de cellules solaires sur verre non trempé, qui sont relativement fragiles et représentent un danger potentiel important car elles se brisent en morceaux coupants. Leur utilisation sur des immeubles se trouve ainsi limitée, voire prohibée pour l'équipement de façades.To date, one must therefore be content with solar cells on non-tempered glass, which are relatively fragile and represent a significant potential hazard because they break into sharp pieces. Their use on buildings is thus limited or even prohibited for facade equipment.

Les brevets US 4 751 149 et 5 002 796 décrivent des procédés de dépôt de la couche d'oxyde en phase vapeur, dans lesquels les composés chimiques participant à la réaction sont amenés à la chambre par un gaz porteur saturé en ces composés par barbotage.US Pat. Nos. 4,751,149 and 5,002,796 disclose methods of depositing the vapor phase oxide layer in which the chemical compounds participating in the reaction are brought to the chamber by a carrier gas saturated with these compounds by bubbling.

Une telle méthode permet, certes, de disposer de conditions de réactions plus douces, qui n'altèrent pas les propriétés du substrat, et donc d'être utilisable, notamment, pour la production de cellules solaires sur verre trempé. Toutefois, la méthode ne permet pas de bien contrôler la quantité de réactifs mise en jeu, car l'équilibre thermodynamique qui régit le seuil de saturation du gaz porteur dépend fortement de la température et du flux de ce gaz. Comme il est problématique de fixer précisément la température dans l'ensemble du circuit, on risque donc d'avoir une recondensation non contrôlée de réactifs en un endroit plus froid de l'installation. La régularité et la reproductibilité de la couche sont, de ce fait, assez difficiles à assurer.Such a method makes it possible, of course, to have softer reaction conditions, which do not alter the properties of the substrate, and therefore to be used, in particular, for the production of solar cells on tempered glass. However, the method does not allow good control of the amount of reagents involved, because the thermodynamic equilibrium that governs the saturation threshold of the carrier gas strongly depends on the temperature and the flow of this gas. Since it is problematic to precisely set the temperature in the entire circuit, there is a risk of uncontrolled recondensation of reagents in a colder place of the installation. The regularity and reproducibility of the layer are, therefore, quite difficult to ensure.

La présente invention a pour but de fournir un procédé de dépôt permettant non seulement l'utilisation d'un substrat en verre trempé ou tout autre matériau résistant mal à des températures élevées (supérieures à 300° C) mais également un contrôle précis de la quantité de réactifs engagés, car les conditions expérimentales régnant dans le circuit d'alimentation sont suffisantes pour éviter toute recondensation intempestive.It is an object of the present invention to provide a deposition method which allows not only the use of a tempered glass substrate or any other material resistant to high temperatures (above 300 ° C). but also a precise control of the amount of reagents involved, because the experimental conditions prevailing in the supply circuit are sufficient to prevent unwanted recondensation.

De façon plus précise, l'invention concerne un procédé de dépôt d'une couche d'oxyde conducteur transparent sur un substrat disposé à l'intérieur d'une enceinte, caractérisé en ce qu'il consiste :

  • à se doter de sources contenant respectivement un composé liquide à base d'oxygène, un composé liquide du métal destiné à former l'oxyde, et un dopant sous forme gazeuse ou liquide,
  • à établir dans l'enceinte une température comprise entre 130 et 300°C et une pression comprise entre 0.01 et 2 mbar, puis
  • à mettre lesdites sources en communication avec l'enceinte, ce qui a pour effet de vaporiser les liquides à leur surface, de les aspirer dans l'enceinte sans avoir à utiliser de gaz porteur, et de les y faire réagir avec le dopant de manière à ce que la couche d'oxyde soit formée sur le substrat.
More specifically, the invention relates to a method for depositing a transparent conductive oxide layer on a substrate disposed inside an enclosure, characterized in that it consists of:
  • to obtain sources respectively containing an oxygen-based liquid compound, a liquid compound of the metal intended to form the oxide, and a dopant in gaseous or liquid form,
  • to establish in the chamber a temperature between 130 and 300 ° C and a pressure between 0.01 and 2 mbar, then
  • to put said sources in communication with the enclosure, which has the effect of vaporizing the liquids on their surface, to suck them into the chamber without having to use carrier gas, and to react with the dopant therein the oxide layer is formed on the substrate.

Selon l'invention, lorsque les températures mentionnées ci-dessus sont trop basses pour permettre les réactions chimiques conduisant à la formation de l'oxyde, la vaporisation chimique s'effectue dans un plasma des gaz de dépôt, formé à l'intérieur de l'enceinte, de préférence en utilisant la technique du PECVD (Plasma Enhanced Chemical Vapor Deposition), bien connue de l'homme de métier.According to the invention, when the temperatures mentioned above are too low to allow the chemical reactions leading to the formation of the oxide, the chemical vaporization is carried out in a plasma of the deposition gases, formed inside the pregnant, preferably using the technique of PECVD (Plasma Enhanced Chemical Vapor Deposition), well known to those skilled in the art.

L'invention concerne également une cellule photovoltaïque caractérisée en ce qu'elle comporte:

  • un substrat,
  • une couche d'oxyde conducteur transparent déposée sur le substrat par le procédé défini précédemment, et
  • une couche photovoltaïquement active déposée sur la couche d'oxyde.
The invention also relates to a photovoltaic cell characterized in that it comprises:
  • a substrate,
  • a transparent conductive oxide layer deposited on the substrate by the method defined above, and
  • a photovoltaically active layer deposited on the oxide layer.

De façon avantageuse, la couche active de la cellule comporte trois sous-couches de silicium hydrogéné amorphe, microcristallin ou nanocristallin formant une jonction p-i-n, les deux sous-couches externes étant respectivement dopées positivement et négativement.Advantageously, the active layer of the cell comprises three sub-layers of amorphous, microcrystalline or nanocrystalline hydrogenated silicon forming a p-i-n junction, the two external sublayers being respectively positively and negatively doped.

Avantageusement, le substrat est en verre, de préférence en verre trempé, mais il peut être aussi en acier inox, en aluminium ou en un polymère.Advantageously, the substrate is made of glass, preferably tempered glass, but it can also be made of stainless steel, aluminum or a polymer.

D'autres caractéristiques de l'invention ressortiront de la description qui va suivre, faite en regard du dessin annexé, dans lequel:

  • la figure 1 est une vue en coupe d'une cellule selon l'invention, et
  • la figure 2 montre schématiquement un équipement pour la fabrication de cette cellule.
Other features of the invention will emerge from the description which follows, given with reference to the appended drawing, in which:
  • FIG. 1 is a sectional view of a cell according to the invention, and
  • Figure 2 schematically shows equipment for the manufacture of this cell.

La cellule représentée sur la figure 1 utilise comme substrat 10 une mince plaque de verre trempé, ayant une épaisseur de l'ordre de 1 à 8 mm, sur laquelle est déposée une couche d'oxyde conducteur transparent (TCO) 12 ayant, typiquement, une épaisseur de 0.2 à 4 µm.The cell shown in FIG. 1 uses as substrate a thin tempered glass plate, having a thickness of the order of 1 to 8 mm, on which is deposited a transparent conductive oxide (TCO) layer 12 having, typically, a thickness of 0.2 to 4 μm.

La couche 12, avantageusement constituée de dioxyde d'étain (SnO2), d'oxyde de zinc (ZnO) ou d'un oxyde d'étain et de zinc, est déposée par vaporisation chimique (CVD) selon un procédé qui sera décrit plus loin.The layer 12, advantageously consisting of tin dioxide (SnO 2 ), zinc oxide (ZnO) or an oxide of tin and zinc, is deposited by chemical vaporization (CVD) according to a process which will be described further.

Une couche photovoltaïquement active 14, ayant une épaisseur d'environ 0.2 à 10 µm, est déposée sur la couche d'oxyde 12. Elle est composée de trois sous-couches de silicium hydrogéné amorphe, microcristallin ou nanocristallin 16, 18 et 20, formant une jonction p-i-n. Les deux sous-couches externes 16 et 20 sont respectivement dopées positivement et négativement.A photovoltaic active layer 14, having a thickness of about 0.2 to 10 μm, is deposited on the oxide layer 12. It is composed of three sublayers of amorphous hydrogenated silicon, microcrystalline or nanocrystalline 16, 18 and 20, forming a pine junction. The two outer sublayers 16 and 20 are respectively positively and negatively doped.

Finalement, la cellule comporte encore une couche de contact arrière 22, par exemple en oxyde de zinc, déposée sur la couche active 14 et une couche réfléchissante 24, par exemple en argent ou en aluminium, déposée sur la couche 22.Finally, the cell further comprises a rear contact layer 22, for example zinc oxide, deposited on the active layer 14 and a reflective layer 24, for example silver or aluminum, deposited on the layer 22.

D'autres structures de cellules, utilisant notamment une jonction n-i-p, peuvent être réalisées sur le même substrat en verre trempé et la même couche d'oxyde transparent. Elles sont décrites en détail dans le document EP déjà cité.Other cell structures, in particular using a nip junction, can be made on the same tempered glass substrate and the same layer of transparent oxide. They are described in detail in the EP document already cited.

On se référera maintenant à la figure 2 qui représente l'équipement permettant le dépôt par CVD d'une couche d'oxyde de zinc 12 sur la plaque de verre trempé 10. Sur cette figure, on a représenté en 26 une enceinte étanche dotée d'un support chauffant 28 sur lequel est déposée la plaque de verre trempé. L'enceinte 26 est raccordée à une pompe à vide 30 ainsi qu'à trois réservoirs 32, 34 et 36 contenant, le premier, de l'eau, le deuxième, du diéthylezinc (C2H5)2Zn et le troisième, un dopant, avantageusement sous la forme de diborane (B2H6). Bien entendu, d'autres composés à base de zinc et d'autres dopants, tous bien connus de l'homme de métier, peuvent être utilisés. Les contenus des deux réservoirs 32 et 34 sont liquides, tandis que celui du réservoir 36 est un mélange gazeux de 0.5 à 2 % de diborane dilué dans un gaz tel que l'azote, l'argon ou l'hydrogène. On notera que les réservoirs 32 et 34 sont reliés directement à l'enceinte. Le réservoir 36 est préalablement raccordé au conduit d'amené du réservoir 34 mais il peut aussi être relié directement à l'enceinte.Referring now to Figure 2 which shows the equipment for the CVD deposition of a layer of zinc oxide 12 on the tempered glass plate 10. In this figure, there is shown at 26 a sealed chamber with a heating support 28 on which is deposited the tempered glass plate. The chamber 26 is connected to a vacuum pump 30 and three reservoirs 32, 34 and 36 containing, first, water, the second, diethyl (C 2 H 5 ) 2 Zn and the third, a dopant, advantageously in the form of diborane (B 2 H 6 ). Of course, other zinc compounds and other dopants, all well known to those skilled in the art, can be used. The contents of the two tanks 32 and 34 are liquid, while that of the tank 36 is a gaseous mixture of 0.5 to 2% of diborane diluted in a gas such as nitrogen, argon or hydrogen. It will be noted that the tanks 32 and 34 are connected directly to the enclosure. The reservoir 36 is pre-connected to the supply conduit of the reservoir 34, but it can also be connected directly to the enclosure.

En fonctionnement, l'enceinte 26 est portée, à l'aide du support chauffant 28, à une température d'environ 180°C, mais qui peut être comprise entre 130 et 300 °C, tandis que la pompe 30 abaisse la pression à une valeur de 0.3 à 0.5 mbar, mais qui peut être comprise entre 0.01 et 20 mbar. Les vannes réglables (non représentées) reliant les réservoirs 32, 34 et 36 à l'enceinte 26 sont alors ouvertes. Du fait de la très faible pression établie dans l'enceinte et donc dans les réservoirs, le diéthylzinc et l'eau contenus dans ces derniers à l'état liquide s'évaporent à leur surface et les gaz résultant, aspirés dans l'enceinte, réagissent entre eux et avec le gaz dopant (B2H6) pour provoquer, à la température du substrat, selon une réaction connue, le dépôt de la couche d'oxyde de zinc désirée 12 sur la plaque de verre trempé 10.In operation, the enclosure 26 is carried, using the heating support 28, at a temperature of about 180 ° C, but may be between 130 and 300 ° C, while the pump 30 lowers the pressure at a value of 0.3 to 0.5 mbar, but which can be between 0.01 and 20 mbar. The adjustable valves (not shown) connecting the reservoirs 32, 34 and 36 to the enclosure 26 are then open. Due to the very low pressure established in the chamber and therefore in the tanks, the diethylzinc and the water contained therein in the liquid state evaporate on their surface and the resulting gases sucked into the chamber, react with each other and with the doping gas (B 2 H 6 ) to cause, at the temperature of the substrate, according to a known reaction, the deposition of the desired zinc oxide layer 12 on the tempered glass plate 10.

L'opération se déroulant à une température relativement peu élevée, le verre trempé ne subit aucune détérioration de ses propriétés. Par ailleurs, compte tenu de la pression homogène et faible régnant dans l'installation, les gaz vaporisés ne risquent pas de se recondenser avant leur admission dans l'enceinte.Since the operation takes place at a relatively low temperature, the tempered glass undergoes no deterioration of its properties. Moreover, given the homogeneous and low pressure prevailing in the installation, the gases sprays are not likely to recondense before admission to the enclosure.

Le procédé ci-dessus convient parfaitement pour le dépôt d'oxyde de zinc dopé au diborane car les réactions chimiques mises en jeu se font sans problème aux températures mentionnées. En revanche, lorsqu'il s'agit d'effectuer un dépôt CVD de dioxyde d'étain ou un dépôt d'oxyde de zinc avec un dopant plus stable tel que le tétrafluorure de méthyle (CF4), ces températures sont trop basses pour que les réactions aient lieu normalement.The above method is ideal for depositing zinc oxide doped with diborane because the chemical reactions involved are without problems at the temperatures mentioned. On the other hand, when it comes to making a CVD deposition of tin dioxide or a deposit of zinc oxide with a more stable dopant such as methyl tetrafluoride (CF 4 ), these temperatures are too low for that the reactions take place normally.

Selon l'invention, le dépôt de la couche d'oxyde est alors réalisé par le procédé de vaporisation chimique sous plasma PECVD. Dans ce cas, l'enceinte 26 est équipée d'une électrode, par exemple en forme de grille 38, disposée au-dessus du support chauffant 28 et un générateur électrique 40 est connecté entre cette électrode et le support.According to the invention, the deposition of the oxide layer is then carried out by the PECVD plasma chemical vaporization method. In this case, the enclosure 26 is equipped with an electrode, for example in the form of a grid 38, disposed above the heating support 28 and an electric generator 40 is connected between this electrode and the support.

Ainsi, en fonctionnement, alors que la température et la pression sont maintenues aux valeurs mentionnées précédemment, les gaz introduits dans l'enceinte 26 donnent lieu à la formation d'un plasma entre l'électrode 38 et le support 28. Des radicaux actifs sont ainsi générés par le plasma et permettent que les réactions chimiques donnant lieu au dépôt de la couche d'oxyde se fassent à une température sensiblement plus basse que celle normalement nécessaire, préservant ainsi les propriétés du substrat.Thus, in operation, while the temperature and the pressure are maintained at the values mentioned above, the gases introduced into the chamber 26 give rise to the formation of a plasma between the electrode 38 and the support 28. Active radicals are thus generated by the plasma and allow the chemical reactions giving rise to the deposition of the oxide layer to be at a temperature substantially lower than that normally required, thus preserving the properties of the substrate.

De façon avantageuse, pour obtenir le dépôt souhaité de SnO2, les réservoirs 34 et 36 contiennent respectivement, par exemple, du tetraméthyleétain (CH3)4Sn et, comme dopant, du tétrafluorure de méthyle (CF4). II va de soi que d'autres composés, bien connus dans la pratique, peuvent être utilisés.Advantageously, to obtain the desired deposit of SnO 2 , the tanks 34 and 36 respectively contain, for example, tetramethyltin (CH 3 ) 4 Sn and, as a dopant, methyl tetrafluoride (CF 4 ). It goes without saying that other compounds, well known in the art, can be used.

On notera que l'eau du réservoir 32 peut être remplacée par tout composé contenant de l'oxygène ( N2O, CH3OH, C2H5OH,...) et que le dopant contenu dans le réservoir 36 peut aussi être sous forme liquide.It will be noted that the water in the reservoir 32 may be replaced by any oxygen-containing compound (N 2 O, CH 3 OH, C 2 H 5 OH, ...) and that the dopant contained in the reservoir 36 may also be be in liquid form.

La présente description a été faite en se référant à un substrat en verre trempé car il trouve une application particulièrement intéressante pour l'équipement de façades, mais il va de soi que d'autres substrats, tels que le verre normal, l'acier inox, l'aluminium ou des polymères,.... peuvent être utilisés dans le cadre de l'invention.The present description has been made with reference to a tempered glass substrate because it finds a particularly interesting application for the equipment of facades, but it goes without saying that other substrates, such as the normal glass, stainless steel, aluminum or polymers, .... can be used in the context of the invention.

Claims (5)

  1. A process for depositing a transparent conductive oxide film (12) on a substrate (10) placed inside a chamber (26), characterized in that it consists in:
    - providing sources (32, 34, 36) containing an oxygen-based liquid compound, a liquid compound of the metal intended to form the oxide, and a dopant in gaseous or liquid form, respectively;
    - establishing a temperature between 130 and 300°C and a pressure between 0.01 and 2 mbar in said chamber; and then
    - bringing said sources into communication with said chamber, which has the effect of vaporizing said liquids at their surface, of drawing them up into the chamber without having to use a carrier gas, and of making them react therein with the dopant so that said oxide layer is formed on the substrate.
  2. The process as claimed in claim 1, for depositing a film of zinc oxide, characterized in that said sources (32, 34, 36) contain water, diethylzinc in liquid form and a diborane-based gas mixture, respectively.
  3. The process as claimed in claim 1, characterized in that it consists, in addition, in forming a plasma of the vaporized liquids inside the chamber.
  4. The process as claimed in claim 3, for depositing a film of tin oxide, characterized in that said sources (32, 34, 36) contain water, tetramethyltin in liquid form and a gas mixture based on methyl tetrafluoride, respectively.
  5. The process as claimed in claim 3, for depositing a film of zinc oxide, characterized in that said sources (32, 34, 36) contain water, diethylzinc in liquid form and a gas mixture based on methyl tetrafluoride, respectively.
EP02754092A 2001-08-30 2002-08-23 Method of depositing an oxide layer on a substrate and a photovoltaic cell using said substrate Expired - Lifetime EP1421630B1 (en)

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EP01810840 2001-08-30
EP01810840A EP1289025A1 (en) 2001-08-30 2001-08-30 Method to deposit an oxyde layer on a substrate and photovoltaic cell using such substrate
EP02754092A EP1421630B1 (en) 2001-08-30 2002-08-23 Method of depositing an oxide layer on a substrate and a photovoltaic cell using said substrate
PCT/CH2002/000458 WO2003021690A2 (en) 2001-08-30 2002-08-23 Method of depositing an oxide layer on a substrate and a photovoltaic cell using said substrate

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EP1421630B1 true EP1421630B1 (en) 2006-10-18

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JP4918224B2 (en) * 2005-01-21 2012-04-18 昭和シェル石油株式会社 Transparent conductive film forming apparatus and multilayer transparent conductive film continuous film forming apparatus
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EP1840966A1 (en) * 2006-03-30 2007-10-03 Universite De Neuchatel Transparent, conducting and textured layer and method of fabrication
JP5559536B2 (en) * 2006-08-29 2014-07-23 ピルキントン グループ リミテッド Method for producing glass article coated with low resistivity doped zinc oxide and coated glass article produced by the process
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CN1326255C (en) 2007-07-11
JP4491233B2 (en) 2010-06-30
EP1421630A2 (en) 2004-05-26
JP2005501182A (en) 2005-01-13
US7390731B2 (en) 2008-06-24
CN1550045A (en) 2004-11-24
ES2274069T3 (en) 2007-05-16
WO2003021690A3 (en) 2003-11-06
AU2002322952A1 (en) 2003-03-18
EP1289025A1 (en) 2003-03-05
DE60215523D1 (en) 2006-11-30
US20040235286A1 (en) 2004-11-25
DE60215523T2 (en) 2007-06-21

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